A standard motor-vehicle door latch has a pivotal latching fork, a release pawl engageable with the fork and displaceable between a latched position retaining the fork in a latched position engaged around a bolt and securing a motor-vehicle door closed and an unlatched position in which the fork can release the bolt and allow the door to open, and a release lever engageable with the pawl for displacing it between its positions and formed with an elongated slot. An outside actuating lever is provided with an entrainment nose aligned with an end of the release-lever slot. Separate inside and outside locking levers are coupled to a main locking lever displaceable thereby between a locked and an unlocked position. A link lever pivoted on the main locking lever carries a coupling pin projecting through the slot and engageable with the entrainment nose on pivoting of the main locking lever into the unlocked position of the main locking lever and unengageable on pivoting of the main locking lever with the entrainment nose into the locked position of the main locking lever. An antitheft lever displaceable between on and off positions is operatively engageable in the on position with the main locking lever to retain it in the locked position.
Normally as described in German patent document 4,433,994 of Kleefeldt the outside actuating lever is connected to the outside door handle and the inside actuating lever with the inside door handle. The outside locking lever is operated by a lock cylinder on the door and the inside locking lever is connected to an inside knob or element. With this system the outside locking lever as well as the link lever decouple the actuating-lever system from the release lever in the locked position of the latch. Thus when locked the outside actuating lever can move but does nothing. The antitheft lever ensures when in the on position that when the door is locked it cannot even be opened by the inside handle.
In another system described in European patent 0,475,037 of Kaiser there is no separate inside locking element. Instead, the inside handle is moved in one direction to lock the door, that is to disconnect or block operation of the door by the outside door handle, and in the opposite direction to simultaneously unlock and unlatch the door.